Clotting disorders common in hormone therapy-related thrombosis

3 September 2010

MedWire News: Women who develop a thromboembolic event (TEE) while taking oral contraceptives or hormone replacement therapy (HRT) have a increased prevalence of clotting disorders, study findings indicate.

“Oral contraceptives and HRT are associated with increased risk for venous and arterial thrombosis,” note Maria DeSancho (Cornell University, New York, USA) and colleagues.

The mechanisms for the increased risk for thrombosis have been attributed, in part, to inherited and acquired clotting disorders (thrombophilias), they add.

To determine the prevalence and types of thrombophilia observed in women with TEEs while taking oral contraceptives or HRT, DeSancho and team retrospectively reviewed the case records of all women referred to the Thrombosis and Hemostasis Section at Mount Sinai Hospital in New York for thrombophilia evaluation over a 4-year period.

The researchers identified 85 women who developed a TEE while taking oral contraceptives or HRT. Of these, 65 (75%) had at least one additional thrombophilia risk factor, and 23 (27%) had more than two types of thrombophilia.

The mean duration for oral contraceptive use (n=47) was 65.2 months, while the mean duration of HRT use (n=18) was 61.8 months.

Among the 65 women with thrombophilias, 26 (40%) had antiphospholipid antibodies, 16 (25%) had the factor V Leiden mutation, 10 (15%) had elevated homocysteine, seven (11%) had protein S deficiency, five (8%) had the prothrombin gene G20210A polymorphism, and four (6%) had protein C deficiency.

The most common TEEs were cerebrovascular events (n=17). There were also 16 pulmonary emboli, 13 deep vein thromboses, 11 intra-abdominal thromboses, five cases of superficial thrombophlebitis, and two retinal vein thromboses.

DeSancho and team note that 23 (35%) patients had a first-degree or second-degree relative with a TEE.

Discussing their findings in the journal Blood Coagulation and Fibrinolysis, the researchers question whether women should be screened for the most common types of thrombophilia prior to being offered oral contraceptives or HRT.

Since several thrombophilias were identified in this study, simply testing for the most common conditions is unlikely to be sufficient to exclude significant thrombophilia, they say.

Despite this, they conclude that “family and personal history of thrombosis should be carefully evaluated in all women before initiating or continuing oral contraceptives or HRT, and a positive history may warrant a thrombophilia screening.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

Blood Coagul Fibrinolysis 2010; 21: 534–538